Q*bert /ˈkjuːbərt/ is an arcade video game developed and published by Gottlieb in 1982. It is a 2D action game with puzzle elements that uses "isometric" graphics to create a pseudo-3D effect, and serves as a precursor to the isometric platformer genre. The object is to change the color of every cube in a pyramid by making the on-screen character hop on top of the cube while avoiding obstacles and enemies. Players use a joystick to control the character.

The game was conceived by Warren Davis and Jeff Lee. Lee designed the title character and original concept, which was then further developed and implemented by Davis. Q*bert was developed under the project name Cubes, but was briefly named Snots And Boogers and @!#?@! during development.

Q*bert was well received in arcades and among critics. The game was Gottlieb's most successful video game and among the most recognized brands from the golden age of arcade video games. It has been ported to numerous platforms. The success resulted in sequels and the use of the character's likeness in merchandising, such as appearances on lunch boxes, toys, and an animated television show. The character Q*bert became known for his "swearing", an incoherent phrase of synthesized speech generated by the sound chip and a speech balloon of nonsensical characters that appear when he collides with an enemy.

Q*bert is an action game with puzzle elements played from an axonometric third-person perspective to convey a three-dimensional look. The game is played using a single, diagonally mounted four-way joystick. The player controls Q*bert, who starts each game at the top of a pyramid made of 28 cubes, and moves by hopping diagonally from cube to cube. Landing on a cube causes it to change color, and changing every cube to the target color allows the player to progress to the next stage.

At the beginning, jumping on every cube once is enough to advance. In later stages, each cube must be hit twice to reach the target color. Other times, cubes change color every time Q*bert lands on them, instead of remaining on the target color once they reach it. Both elements are then combined in subsequent stages. Jumping off the pyramid results in the character's death.

A collision with purple enemies is fatal to the character, whereas the green enemies are removed from the board upon contact. Colored balls occasionally appear at the second row of cubes and bounce downward; contact with a red ball is lethal to Q*bert, while contact with a green one immobilizes the on-screen enemies for a limited time. Multicolored floating discs on either side of the pyramid serve as an escape from danger, particularly Coily. When Q*bert jumps on a disc, it transports him to the top of the pyramid. If Coily is in close pursuit of the character, he will jump after Q*bert and fall to his death, awarding bonus points. This causes all enemies and balls on the screen to disappear, though they start to return after a few seconds.

Points are awarded for each color change (25), defeating Coily with a flying disc (500), remaining discs at the end of a stage (at higher stages, 50 or 100) and catching green balls (100) or Slick and Sam (300 each). Extra lives are granted for reaching certain scores, which are set by the machine operator.

The basic ideas for the game were thought up by Warren Davis and Jeff Lee. The initial concept began when artist Jeff Lee drew a pyramid of cubes inspired by M. C. Escher. Lee felt a game could be derived from the artwork, and created an orange, armless main character. The character jumped along the cubes and shot projectiles, called "mucus bombs", from a tubular nose at enemies. Enemies included a blue creature, later changed purple and named Wrong Way, and an orange creature, later changed green and named Sam. Lee had drawn similar characters since childhood, inspired by characters from comics, cartoons, Mad magazine and by artist Ed "Big Daddy" Roth. Q*bert's design later included a speech balloon with a string of nonsensical characters, "@!#?@!",[Note 1] which Lee originally presented as joke.

Warren Davis, a programmer hired to work on the action game Protector, noticed Lee's ideas, and asked if he could use them to practice programming randomness and gravity as game mechanic. Thus, he added balls that bounced from the pyramid's top to bottom. Because Davis was still learning how to program game mechanics, he wanted to keep the design simple. He also felt games with complex control schemes were frustrating and wanted something that could be played with one hand. To accomplish this, Davis removed the shooting and changed the objective to saving the protagonist from danger. As Davis worked on the game one night, Gottlieb's vice president of engineering, Ron Waxman, noticed him and suggested to change the color of the cubes after the game's character has landed on them. Davis implemented a unique control scheme; a four-way joystick was rotated 45° to match the directions of Q*bert's jumping. Staff members at Gottlieb urged for a more conventional orientation, but Davis stuck to his decision. Davis remembered to have started programming in April 1982, but the project was only put on schedule as an actual product several months later.

The Gottlieb staff had difficulty naming the game. Aside from the project name "Cubes", it was untitled for most of the development process. The staff agreed the game should be named after the main character, but disagreed on the name. Lee's title for the initial concept—Snots And Boogers—was rejected, as was a list of suggestions compiled from company employees. According to Davis, vice president of marketing Howie Rubin championed @!#?@! as the title. Although staff members argued it was silly and would be impossible to pronounce, a few early test models were produced with @!#?@! as the title on the units' artwork. During a meeting, "Hubert" was suggested, and a staff member thought of combining "Cubes" and "Hubert" into "Cubert". Art director Richard Tracy changed the name to "Q-bert", and the dash was later changed to an asterisk. In retrospect, Davis expressed regret for the asterisk, because he felt it prevented the name from becoming a common crossword term and it is a wildcard character for search engines.

Q*bert was Gottlieb's only video game that gathered huge critical and commercial success, selling around 25,000 arcade cabinets. Cabaret and cocktail versions of the game were later produced. The machines have since become collector's items; the rarest of them are the cocktail versions.